1. Field of the Invention
The present invention relates to a motor driving device and a motor control method.
2. Description of the Related Art
Generally, in the case of a motor capable of controlling a speed such as a BLDC motor, the speed can be controlled by controlling a duty value of a pulse-width-modulation (PWM) signal. The duty value of the pulse-width-modulation signal may be determined according to a turn-on time when a signal has a high value and a turn-off time when a signal has a low value, within a single period, and a rotational speed of a motor may be in proportion to the duty value of the pulse-width-modulation signal.
A method for controlling a speed of a motor may be classified as an open loop control method and a closed loop control method. The open loop control method does not include a feedback circuit and therefore, may have a simple structure, but cannot compensate for errors occurring due to external factors such as electrical noise, a change in temperature, and the like. On the other hand, the closed loop control method includes a feedback circuit to detect the current revolutions per minute (RPM) and speed of the motor, the operation environment around the motor, and the like, and controls an input signal therefrom to control errors occurring at the time of the operation of the motor.
In the case of the closed loop control method, the speed of the motor is fedback, such that the motor can maintain a constant speed at all times, but when the speed of the motor is reduced by the external input signal, the motor stops due to overshoot.